add devFunds contract

Signed-off-by: therealsakeswap <[email protected]>

contracts/DevFunds.sol

@@ -0,0 +1,36 @@
+pragma solidity 0.6.12;
+
+import "@openzeppelin/contracts/math/SafeMath.sol";
+import "./SakeToken.sol";
+
+contract DevFunds {
+    using SafeMath for uint;
+
+    // the sake token
+    SakeToken public sake;
+    // dev address to receive sake
+    address public devaddr;
+    // last withdraw block
+    uint public lastWithdrawBlock;
+    // withdraw interval about 1 month
+    uint public constant WITHDRAW_INTERVAL = 194800;
+    // max amount of sake per withdraw
+    uint public constant WITHDRAW_MAX = 68*10**22;
+
+    constructor(SakeToken _sake, address _devaddr) public {
+        require(address(_sake) != address(0) && _devaddr != address(0), "invalid address");
+        sake = _sake;
+        devaddr = _devaddr;
+        lastWithdrawBlock = block.number;
+    }
+
+    function withdraw() public {
+        uint unlockBlock = lastWithdrawBlock.add(WITHDRAW_INTERVAL);
+        require(block.number >= unlockBlock, "sake locked");
+        uint _amount = sake.balanceOf(address(this));
+        uint amountReal = _amount > WITHDRAW_MAX ? WITHDRAW_MAX : _amount;
+        require(amountReal > 0, "zero sake amount");
+        lastWithdrawBlock = block.number;
+        sake.transfer(devaddr, amountReal);
+    }
+}

test/DevFunds.test.js

@@ -0,0 +1,26 @@
+const { expectRevert, time } = require('@openzeppelin/test-helpers');
+const SakeToken = artifacts.require('SakeToken');
+const DevFunds = artifacts.require('DevFunds');
+
+contract('DevFunds', ([alice, bob, carol]) => {
+    beforeEach(async () => {
+        this.sake = await SakeToken.new({ from: alice });
+        this.devFunds = await DevFunds.new(this.sake.address, bob, { from: alice });
+        this.withdrawInternal = await this.devFunds.WITHDRAW_INTERVAL();
+        this.maxWithdraw = await this.devFunds.WITHDRAW_MAX();
+    });
+
+    it('should revert before lockTime', async () => {
+        await expectRevert(this.devFunds.withdraw({ from: alice }), 'sake locked');
+        const currentBlock = await time.latestBlock();
+        const unlockBlock = parseInt(currentBlock) + parseInt(this.withdrawInternal);
+        await time.advanceBlockTo(unlockBlock);
+        await expectRevert(this.devFunds.withdraw({ from: alice }), 'zero sake amount');
+        await this.sake.mint(this.devFunds.address, '1000000000000000000000000');
+        await this.devFunds.withdraw({ from: alice });
+        const bal = await this.sake.balanceOf(bob);
+        assert.equal(bal.valueOf(), parseInt(this.maxWithdraw));
+        const lastWithdrawBlock = await this.devFunds.lastWithdrawBlock();
+        assert.equal(lastWithdrawBlock.valueOf(), unlockBlock + 3);
+    });
+})